1. Field of the Invention
The present invention relates generally to an automatic flaw removing method for long materials. More specifically, the invention relates to an automatic flaw removing method, which inspects long materials, such as round-bar steels and steel pipes, for surface flaws by means of a flaw detecting apparatus of all section to automatically grind the materials having a flaw(s) on the basis of the flaw-position information.
2. Description of the Prior Art
As an example of a conventional automatic flaw removing method for long materials, Japanese Patent Publication No. 52-15054 discloses "a flaw-position defining method in a separate automatic flaw removing apparatus". In this method, a flaw inspecting apparatus is arranged so as to be separated from a grinder. In addition, during inspection, a reference point, such as a label which can be detected by optical means, is provided on a material to be processed. During grinding, the reference point is compared with the positional information of a flaw(s) detected by an optical detector to control the grinding position of the grinder.
In such a conventional method, as described above, a label is attached to a material to be detected, such as a round-bar steel, or a quick drying ink or paint is sprayed thereon. Therefore, the conventional method is not sufficient to accurately define the positions of the flaws, various flaw-patterns and so forth. In particular, it is difficult to apply the conventional method to a line of a high flaw-detecting rate (e.g., above 100 m/min), a material of a small-diameter curve and so forth.
In addition, in a case where an ultrasonic flaw detector using water is located immediately downstream of a surface inspecting apparatus, the label may be removed or the marking may run, so that it is difficult to apply the conventional method to an automatic flaw removing apparatus, which is required to have the accuracy and certainty of the position of the origin.
Moreover, during flaw detection, the material may travel while being twisted due to friction on a carrier roll and so forth. When a single reference mark is used, the flaw-position information map may also be twisted to be inaccurate, so as to cause the dislocation of the automatic grinding.